Oscillating system for derrick booms



Nov. 11, 1958 M. J. PURETIC 2,859,882

OSCILLATING SYSTEM FOR DERRICK BOOMS Filed July 2, 1957 2 Sheets-Sheet 1ivy- INVENTOR Mane/ 0 J PMQEr/O ATTORNEY Nov. 11, 1958 M. J. PURETICOSCILLATING SYSTEM FOR DERRICK BO OMS 2 Sheets-Sheet 2 Filed July 2,1957 INVENTOR MAP/0 J. PueET/c ATTORNEY My 5 W.

limited State OSCILLATHNG SYSTEMFQR DEICK 'BOOMS Mario J; Puretic,Torrance, Calif.

Application July 2, 1957, Serial No. 669,620

10 Claims. (Cl. 212-66) This invention relates to hoisting apparatusprimarily for use on shipboard and more particularly to a mechanism forautomatically providing an oscillating movement to the boom of suchhoisting apparatus in order to move the same back and forth through apredetermined are, such swinging movement being continuous andautomatic.

Whilethe. apparatus of. this invention may be utilized in anyinstallation whereit is desired to continuously and automaticallyoscillate the boom of a derrick through a predetermined arc, the primarypurpose of this invention ,is to provide an apparatus for use infacilitating fishing operations in which a relatively long net, commonlycalled a seine, must be hoisted from the water and stacked on the deckof the fishing vessel. Heretofore, it has been customaryto hoist theseine from the water and to manually lay the same in folds on the deckof the vessel as the seine is lowered by the derrick, but since suchseines are relatively heavy, considerable manual exertion is required onthe part of severalmen and consequently, any apparatus which willperform this operation automatically thereby eliminating the necessityof manual operations will materially reduce the cost of such fishingoperation.

It is accordingly an object of the invention to provide an automaticoscillating system for derrick booms which may be conveniently appliedto existing equipment without material-modification thereof or which maybe con veniently and economically included during the manufacture ofsuch equipment.

A further object of the invention is the provision of an automaticoscillating system for derrick booms in whichthe are through which theboom oscillates may be conveniently adjusted andwith the center of suchoscilla- 'tion disposed at any desired angular position.

A still further object of the invention is the provision of an automaticoscillating system for derrick booms in which fluid pressure maybeutilized to swing a boom to and fro through a predetermined arc and overany desired portion of the deck of a vessel or the surface below theboom.

Another object of the invention is the provisionof an automaticoscillating system for derrick booms in which double acting fluidpressure operated cylinders are utilized to swing the boom to and froand in which the operation of such cylinders are automaticallycontrolled by a simple atent o 2 ing the oscillating system of thisinvention andlfurther showing the arrangement of the cables utilized toswing the derrick boom from one side to the other;

Fig. 2 a side elevational viewshowinga portion of a derrick mast andboom, together with the oscillating systern of this invention .and themanner in which the sarne is installed;

Fig. 3 a sectional view taken. substantially on;.the line 33 of Fig. 2andshowingthe valveactuating lever shifting'members disposed in positionto maintain the boom substantially in a fore and aft position;

Fig. 4 a sectional view .taken substantially on .the' line d-4 of Fig. 2and showing the valve actuating lever shifting members disposed inposition to cause oscillationof the derrick boom through a predeterminedarc and showing in dotted lines the extrerne positi onof the boom andshifting members prior to reversal of the oscillating mechanism;

Fig. 5 a fragmentary sectional view taken substantially on the line 5.-5of Fig. 4 and showing the mechanism utilized to lock the shiftingmembers in adjusted position; and

Fig. 6 a fragmentary sectional view taken substantially on the line 6-6,of Fig. 4 and showing the ,yieldable actuating lever engaging means onthe shifting members.

With continued reference to thedrawing, th'ere is shown a derrick mast10 upon which may bempunted atiany desired location a collar 11 whichserves to pivotally support a king pin 12 for movementabout a verticalaxis. King pin '12, may be provided at the upper end thereof with spacedears 13 and a pivot pin 14extending,thro ugh the ears 13 servestopivotally mount the lower end j15 of a boom 16 for movement about ahorizontal axis.

The boom 16 may beprovided with lugs 17 and 18 extending from oppositesides thereof adjacenttheflower end 15 and fluid pressure operatedcylinder 19 maybe provided at the lower end with spaced ears 20 whichare received over the 111517 and a fastening member21 extending throughthe ears'20 and'lug 17 serves to secure the cylinder 19 at the lower endto the boom 16. In a similar manner, a second fluid pressure operatedcylinder 22 may beprovided with spaced cars .23 which are received overthe lug 18 and pivotallysecured theretof by suitable fastening means 24in order to secure the cylinder 22 to the boom 16 adjacent the lowerendthereof.

Cylinder 19 may be provided with a double actingpiston 25 to whichisconnected a ram 26 projectingfrom. the upper end of the cylinder 19 andat the. upper end of the ram 26 there is'mounte'd a pulley 27. Injasimilar manner, the cylinder 22 may be provided with a double actingpiston to which is attached a ram 28 extending from the upper end of thecylinder 22 and at the upper end of the ram 28 there is mounted a pulley.29.

As best shown in Fig. 1, the boom 16 may be provided at the upper orhead end thereof with head pulleys 30 and 31 disposed on opposite sidesof the boom 16 and a flexible cable 32 of suitable material is trainedover the head pulley 3t and downwardly around .the pulley 27 on the ram26 with the adjacent end33 of the. cable 32Qbejing attached to the boom16 outwardly-of ,the outermost point of travel of the ram 26. Theopposite end.3.4. of the cable 32 is secured to a fixed member 35,whichqin the case of a marineinstallation, may be az partof the boat onwhich the apparatus is installed. In asimilar manner, a flexible-cable36is trained overthe head pulley 31 and downwardly around pulley 29'on-the ram.28 with the adjacent end 37 of the cable 36 being attached.to theboom 16 at a point outwardly of the outermost 451"Fluid pressureoperated cylinder 19 may be connected to ,the control valve 40 throughsuitable flexible jcon'duits 4mm 47 and the operation of cylinder 19 may.j 'oecontrolled by the actuating member 42. In a similar r smay beprovided with a hand engaging knob "niahner, fluid pressure operatedcylinder 22 may be con- "nected to the emitter valve 40 through suitableflexible "conduits" 48 and '49 and cylinder 22'may be controlled.by'tlie valve actuating'lever 43. A fluid pressure supply "conduit 50maybe connected to any suitable fluid presfsure'sourc'e, such as a pumpand to the valve 40 and a .1 fluid pressure discharge conduit 51 mayalso'be connected 'to' the control valve 40 and to a fluid pressuresupply tank or sump to which the fluid pressure pump may be connected. ISince" the fluid pressure operated cylinders 19 and 22 are doubleacting, it will be seen that upon actuation of the valve actuatinglevers 42 and 43 in either direction, that fluid pressure will beintroduced to the cylinders 19 and '22 to either project-the rams 26 and28 therefrom orto retract such rams within the cylinders. As will beseen from an inspection of Fig. 1, retraction of the ram I 26 andprojection of the ram 28 will serve to shorten the cable. 32 and, at thesame time, lengthen the cable 36 thereby swinging the boom 16 toward thefixed member 35 and operation of the rams 26 and'28 in the oppositedirections will serve to swing the boom 16 in the opposite directiontoward the fixed member 39. The length of the arc through which the boom16 moves will, of course, be controlled by the length of travel of ther'ams26 and 28 in the cylinders 19 and 22. In order to provide automaticoperation of the actuating levers 42 and 43 to provide continuousautomatic I oscillation of the boom 16, a substantially semi-circularplate 52'may be fixed to the king pin 12 by means of a set screw 53 orother suitable fastening means for move- "me'ntwith the king pin 12during swinging movement of the boom 16. The plate 52 may also beretained on the lower end of the king pin 12 by means of a nut or other,suitable'fastening means 54. Adjacent theperiphe'ry of the semi-circularplate 52 there may be pro- "vided an arcuate slot 55 and a suitabledegree scale 56 maybe provided on the plate 52 adjacent the slot 55. YAsubstantially semi-circular opening 57 is provided in the plate 52 andthe actuating levers 42 and 43 of the reversing valve 40 projectupwardly through the opening 57 to permit free oscillating movement ofthe plate 52.

Opposed actuating lever shifting members 58 and 59 are disposed onopposite sides of the actuating levers 42 and 43 and the inner ends 60and 61 of the shifting members 58 and 59respectively are mounted forfree pivotal 'movement on the king pin 12 above the semi-circular fplate 52. Shifting member 58 is provided adjacent the outer'en'd 62thereof with clamp means comprising a "bolt" 63 extending downwardlythrough the slot 55 in the plate 52, there being provided at the lowerend of the bolt 63 a head 64 and a washer 65 engaging the lower surfaceofthe plate 52. A finger engaging knob 66 is threadedly received on theupper end of the bolt 63 and serves to clamp the shifting member 58 inadjusted angular position with relation to the semi-circular plate 52.In a similar manner, the shifting member 59 is provided adjacent theouter end 67 thereof with a bolt 68 I extending through the slot 55 inthe plate 52 and a finger H engaging knob 69 threadedly engaging theupper end of the .;bolt 68 s erves to clamp the shifting member 59' in 4I adjusted angular position with relation to the semi-circular plate 52.

Shifting member 58 may be provided with actuating lever engaging means70 and 71, while shifting member 59 may be provided with actuating leverengaging means 72 and 73. Each of the actuating lever engaging means maybe similarly constructed and as best shown in Fig. 6, such means maycomprise a plunger 74 slidably received in a bore 75 in-the shiftingmembers 58 and 59 and sliding movement of the plunger 74 may berestricted by a pin 76 disposed in a slot 77. Other means forrestricting movement of the plunger 74 may, of course, be employed ifdesired. The plunger 74 may be yieldably urged to outer position by acompression spring 78 disposed in the bore 75 and engaging the plunger74 and the tension of spring 78 may be conveniently controlled by ascrew threaded member 79 threadedly received in the shifting members 58and 59 and provided with a washer or other, suitable means 80 engagingthe compression spring 78. The screw threaded member 79 may be providedwith a wrench receiving portion 81 to permit convenient adjustmentthereof.

In the operation of the apparatus of this invention, the shiftingmembers 58 and 59 may be set at any desired angular position, as shownin full lines in Fig. 4, and it may be assumed that the valve actuatinglevers 42 and 43 are in neutral position and the boom 16 in a fore andaft position. It is also to be assumed that fluid pressure is suppliedin the valve 40 through the conduit 50 and when it is desired to placethe apparatus in operation, the hand engaging knobs 44 and on theactuating levers 42 and 43 may be moved in one direction to introducefluid pressure to the cylinders 19 and 22 thereby resulting in swingingmovement of the boom 16 in one direction. Assuming that the actuatinglevers 42 and 43 are moved toward the shifting member 59 as viewed inFig. 4, this will result in movement of the boom 16 in acounter-clockwise direction until the actuating levers 42 and 43 areengaged by the means 72 and 73 on the shifting member 59 which willresult in moving the actuating levers 42 and 43 to a position to'reversethe operation of the cylinders 19 and 22 thereby swinging the boom 16 inthe opposite direction. The position at which movement of the actuatinglevers '42 and 43 takes place to reverse the swinging movement of theboom 16 is shown in dotted lines in Fig. 4. Upon completion of themovement of the boom 16 in the opposite or clockwise direction as shownin Fig. 4, the actuating I boom 16 in the opposite direction. Thisoscillating movement of the boom 16 will automatically continue untilsuch time as the actuating levers 42 and 43 are manually moved toneutral position.

It will therefore be seen that a seine suspended from the head or upperend of the boom .16 and being continuously hoisted from the water andlowered toward the deck of the vessel will be laid in folds on the deckof the vessel and set in a uniform manner.

When it is desired to secure the boom 16 in a fore and aft position uponcompletion of fishing operations or for any other purpose, the shiftingmembers 58 and 59 may be disposed in the position shown in Fig. 3 inwhich, the actuating levers 42 and 43 are simultaneously engaged by themeans 70 and 71, as well as the means 72 and 73 on both of the shiftingmembers 58 and 59.

This, of course, will operate to maintain the levers 42 and 43 inneutral position.

4, the swinging movement of the boom 16 will be uniform about a fore andaft line, but, of course, if desired, the Q shi ting m m er 5% an 5 a bag iv t s tq-gw a-swingingmovement centered about a linerat an angle tothe fore and aft line of the vessel.

It will, therefore, be seen that the apparatus of this invention willoperate to eflicien'tly stack a seine on the deck of a vessel in foldsof any desired length and will thereby eliminate the necessity of manualhandling of the net during recovery thereof from the water therebymaterially reducing the cost of fishing operations.

While the apparatus of this invention has been described primarily foruse on a fishing vessel, nevertheless,-it will be obvious that the samemay be utilized for any installation where a continuous automatic ormauual oscillation of the boom of aderrick is required or advantageousand the apparatus of this invention is=of such nature, that the same maybe conveniently installed on any-existing derrick, installation or,'ofcourse, may be incorporated in new installations.

Itwill be obvious tothose skilled in the art that various changes may bemade in the invention without departing from the spirit and scopethereof and therefore the invention is not limited by that which isshown inthe sure cylinders mounted on opposite sides of said boomadjacent the lower end, a ram projecting from the upper end of eachcylinder, a pulley on the upper end of each ram, a pair of head pulleyssecured to the upper end of said boom on opposite sides, a pair ofcables trained over .said head pulleys and around the pulleys on saidram with the adjacent ends of said cables fixed to said boom outwardlyof the outermost point of travel of said rams, the opposite ends of saidcables beingfixedattransversely spaced points in alignment with saidking pin, a reversing control valve for each cylinder, conduitsconnecting 'said cylinders and said valves, a fluid pressure supplyconduit and a fluid pressure discharge conduit connected 'to saidvalves, an actuating lever on each valve, a sub stantially semi-circularplate fixed to said king pin for movement therewith, an arcuate slot insaid plate adjacent the periphery, a substantially semi-circular openingin said plate through which said actuating levers project, opposedactuating lever shifting members disposed on opposite sides of saidactuating levers, said members being mounted at one end for free pivotalmovement on said king pin, clamp means at the opposite end of eachmember extending through said slot for fixing each member in adjustedangular position and yieldableactuating lever engaging means on eachmember whereby said levers and control valves will be periodicallyactuated to alternately connect said fluid pressure supply conduit tosaid cylinders to lengthen and shorten said cables thereby continuouslyand automatically swinging said boom back and forth through an aredetermined by the position of said members on said plate.

2. An automatic oscillating system for derrick booms, said systemcomprising a king pin mounted for pivotal movement about a verticalaxis, a boom pivotally connected at the lower end to said king pin formovement about a horizontal axis, a pair of double acting fluid pressurecylinders mounted on opposite sides of said boom adjacent the lower end,a ram projecting from the upper end of each cylinder, a pulley on theupper end of each ram, a pair of head pulleys secured to the upper endof said boom on opposite sides, a pair of cables trained over said headpulleys and around the pulleys on said rams with the adjacent ends ofsaid cables fixed to said 'boom outwardly of the outermost point oftravel of said rams, :the opposite ends of said cables being fixed at:transversely spaced points in alignment with said king 6 pin, areversing. control valve for each .cylinder, conduits connecting saidcylindersand said valves, a fluid pressure supply conduit and a fluidpressure discharge .conduit connected to said valves, an actuating leveron each valve, a substantially semi-circular plate fixed to said kingpin for movement therewith. an arcuate slotin said plate, asubstantially semi-circular opening .insaid plate through which saidactuating levers project, opposedtactuating levershifting membersdisposed on opposite'sides of said actuating levers, said members beingvmounted at one end for free pivotal movement on "said kingpin, clampmeans at the opposite :end of each member extending through said slotfor fixing each :member in adjusted angular position and actuating leverengaging means on each member whereby said levers and control valveswill be periodically actuated toalternatelyconnectr said fluid pressuresupply conduit to saidrcylinders to'lengthen and shorten said cablesthereby continuously and 'automatically swinging said boom back andforththrough'an are determined by the position of said members onsaidplate.

3. An automatic oscillating system for derrick booms, said systemcomprising a king pin mounted for pivotal movement about a verticalaxis, a boom connected at the lower end to said king pin, a pair ofdouble acting fluid pressure cylinders mounted on opposite sides of said'boom adjacent the lower end, a ram projecting fromthe upper end of eachcylinder, a pulley on the upperend of each ram, a pair of head pulleyssecured to "the upper end of said boom on opposite 'sides, a pair ofcables trained over said head pulleys and around the pulleys on saidrams with the adjacent ends of said cables fixed to said boom outwardlyof the outermost pointoftravel of said rams, the oppositeends of saidcables'being fixed at transversely spaced points in alignment-with saidkiug pin, a reversing control valve for each cylinder, conduitsconnecting said cylinders and said valves, a fiuidpressure supplyconduit and a fluid pressure discharge conduit connected to said valves,an actuating'lever on each valve, a substantially semi-circular platefixed -to said king pin for movement therewith, an arcuate slot 'in'said plate, a substantially semi-circular opening in said plate throughwhich said actuating levers project, opposed actuating lever shiftingmembers disposed on opposite sides of said actuating levers, saidmembers being mounted-at one end for free pivotal movement on said kingpin,

. clamp means at the opposite end of each member extending through saidslot for fixing each member in adjusted angular position and actuatingleverengagingmeans on each member'whereby said levers and control valveswill be periodically actuated to alternately connect said'fiuid pressuresupply conduit to said cylinders to lengthen and shorten said cablesthereby continuously and automatically swinging said boom back andforththrough an ail'c determined by the position of said members on saidp ate.

4. An automatic oscillating system for derrick booms, said systemcomprising a king pin mounted for pivotal movement about a verticalaxis, a boom connected at'the lower end to said king pin, a pair ofdouble acting fluid pressure cylinders mounted on opposite sides of saidboom adjacent thelower end, a ram projecting fromthe upper end of eachcylinder, a pulley onthe upper end of each ram, a pair of head pulleyssecured to the upper end of said boom on opposite sides, a pair ofcables trained over said head pulleys and around the pulleys on saidrams with the adjacent ends of said cables fixed to said boom outwardlyof the outermost point of travel of said rams, the opposite ends of saidcables being fixed at transversely spaced points, a reversing controlvalve for each cylinder, conduits connecting said cylinders and saidvalves, a fluid pressure supply conduit and afluid pressure dischargeconduit connected to said valves, an actuating lever on each valve, asubstantially semi-circular plate fixed to said king pin for movementtherewith, an arcuate 7 slot in said plate, a substantiallysemi-circular opening in said plate through which said actuating leversproject, opposed actuating lever shifting members disposed on opposltesides of said actuating levers, said members being mounted at one endfor free pivotal movement on said 'king pin, clamp means at the oppositeends of each member extending through said slot for fixing each memberin adjusted angular position and actuating lever engaging means on eachmember whereby said levers and control valves will be periodicallyactuated to alternately connect said fluid pressure supply conduit tosaid cylinders to lengthen and shorten said cables thereby continuouslyand automatically swinging said boom back and forth through an aredetermined by the position of said members on said plate.

5. An automatic oscillating system for derrick booms, said systemcomprising a king pin mounted for pivotal movement about a verticalaxis, a boom connected at the lower end to said king pin, a pair ofdouble acting fluid pressure cylinders mounted on opposite sides of saidboom adjacent the lower end, a ram projecting from the upper end of eachcylinder, a pulley on the upper end of each ram, a pair of head pulleyssecured to the upper end of said boom on opposite sides, a pair ofcables trained over said head pulleys and around the pulleys on saidrams with the adjacent ends of said cables fixed to said boom outwardlyof the outermost point of travel of said rams, the opposite ends of saidcables being fixed at transversely spaced points, a reversing controlvalve for each cylinder, conduits connecting said cylinders and saidvalves, a fluid pressure supply conduit and a fluid pressure dischargeconduit connected to said valves, an actuating lever on each valve, aplate fixed to said king pin for movement therewith, an arcuate slot insaid plate, a substantially semi-circular opening in said plate throughwhich said actuating levers project, opposed actuating lever shiftingmembers disposed on opposite sides of said actuating levers, saidmembers being mounted at one end for free pivotal movement on said kingpin, clamp means at the opposite end of each member extending throughsaid slot for fixing each member in adjusted angular position andactuating lever engaging means on each member whereby said levers andcontrol valves will be periodically actuated to alternately connect saidfluid pressure supply conduit to said cylinders to lengthen and shortensaid cables thereby continuously and automatically swinging said boomback and forth through an are determined by the position of said memberson said plate.

6. An automatic oscillating system for derrick booms,

said system comprising a king pin mounted for pivotal movement about avertical axis, a boom connected at the lower end to said king pin, apair of double acting fluid -.pressure cylinders mounted on oppositesides of said boom adjacent the lower end, a ram projecting from theupper end of each cylinder, a pulley on the upper end of each ram, apair of head pulleys secured to said boom on opposite sides, a pair ofcables trained over said head pulleys and around the pulleys on saidrams with the adjacent .ends of said cables fixed to said boom outwardlyof the outermost point of travel of said rams, the opposite ends of saidcables being fixed at transversely spaced points,-a reversing controlvalve for each cylinder, conduits connecting said cylinders and saidvalves, a fluid pressure supply conduit and a fluid pressure dischargeconduit connected to said valves, an actuating lever on each valve, aplate fixed to said king pin for movement therewith, an arcuate slot insaid plate, a substantially semi-circular opening in said plate throughwhich said actuating levers project, opposed actuating levers shiftingmembers disposed on opposite sides of said actuating levers, saidmembers being mounted at one end for free pivotal movement on said kingpin, clamp means at the opposite end of each member extending throughsaid slot for fixing each member in adjusted angular position andactuating lever engaging means on each member whereby said levers andcontrol valves will ,be periodicallyactuated to alternately connectsaidfluid pressure supply conduit to said cylinders to lengthen andshorten said cables thereby continuously and automatically swinging saidboom back and forth through an are determined by the position of saidmembers on said plate.

7. An automatic oscillating system for derrick booms, said systemcomprising a king pin mounted for pivotal movement about a verticalaxis, a boom connected at the lower end to said king pin, a pair ofdouble acting fluid pressure cylinders mounted on opposite sides of:said boom adjacent the lower end, a ram projecting from the upper end ofeach cylinder, a pulley on the upper end of each ram, a pair of headpulleys secured to said boom on opposite sides, a pair of cables trainedover said head pulleys and around the pulleys on said rams with theadjacent ends of said cables fixed to said boom, the opposite ends ofsaid cables being fixed at transversely spaced points, a reversingcontrol valve for each cylinder, conduits connecting said cylinders andsaid valves, a fluid pressure supply conduit and a fluid pressuredischarge conduit connected to said valves, an actuating lever on eachvalve, a plate fixed to said king pin for movement therewith, an arcuateslot in said plate,'a substantially semi-circular opening in said platethrough which said actuating levers project, opposed actuating levershifting members disposed on opposite sides of said actuating levers,said members being mounted at one end for free pivotal movement on saidking pin, clamp means at the opposite end of each member extendingthrough said slot for fixing each member in adjusted angular positionand actuating lever engaging means on each member whereby said leversand control valves will be periodically actuated to ultimately connectsaid fluid pressure supply conduit to said cylinders to lengthen andshorten said cables thereby continuously and automatically swinging saidboom back and forth through an are determined by the position of saidmember on said plate.

8. An automatic oscillating system for derrick booms, said systemcomprising a king pin mounted for pivotal movement about a verticalaxis, a boom connected at the lower end to said king pin, a pair ofdouble acting fluid pressure cylinders mounted on opposite sides of saidboom adjacent the lower end, a ram projecting from the upper end of eachcylinder, a pulley on theupper end of each ram, a pair of head pulleyssecured to said boom 1 on opposite sides, a pair of cables trained oversaid head pulleys and around the pulleys on said rams with the adjacentends of said cables fixed to said boom, the opposite ends of said cablesbeing fixed at transversely'spaced points, a reversing control valveforeach cylinder, conduits connecting said cylinders and said valves, afluid pressure supply conduit and a fluid pressure discharge conduitconnected to said valves, an actuating lever on each valve, a platefixed to said king pin for movement therewith, an arcuate slot in saidplate, an opening in said 7 V plate through which said actuating leversproject, op-

posed actuating lever shifting members disposed on opposite sides ofsaid actuating levers, said members being mounted at one end for freepivotal movement on said king pin, clamp means on each member extendingthrough said slot for fixing each member in adjusted angular positionand actuating lever engaging means on each member whereby said leversand control valves will be periodically actuated to alternately connectsaid fluid pressure supply conduit to said cylinders to lengthen andshorten said cables thereby continuously and automatically swinging saidboom back and forth through an are determined lower end to said kingpin, a pair of double acting fluid pressure cylinders mounted on saidboom adjacent the i lower end, a ram projecting from the upper end ofeach cylinder, a pulley on the upper end of each ram, a pair of headpulleys secured to said boom, a pair of cables trained over said headpulleys and around the pulleys on said rams with the adjacent ends ofsaid cables fixed to said boom, the opposite ends of said cables beingfixed at transversely spaced points on opposite sides of said boom, areversing control valve for each cylinder, conduits connecting saidcylinders and said valves, a fluid pressure supply conduit and a fluidpressure discharge conduit connected to said valves, an actuating leveron said valves, a plate fixed to said king pin for movement therewith,an arcuate slot in said plate, an opening in said plate through whichsaid actuating levers project, opposed actuating lever shifting membersdisposed on opposite sides of said actuating levers, said members beingmounted at one end for free pivotal movement on said king pin, clampmeans on each member extending through said slot for fixing each memberin adjusted angular position and actuating lever engaging means on eachmember whereby said levers and control valves will be actuated toalternately connect said fluid pressure supply conduit to saidcylinders, to lengthen and shorten said cables thereby continuously andautomatically swinging said boom back and forth through an arcdetermined by the position of said members on said plate.

10. An automatic oscillating system for derrick booms, said systemcomprising a king pin mounted for pivotal movement about a verticalaxis, a boom connected at the lower end to said king pin, a pair ofdouble acting fluid pressure cylinders mounted on said boom adjacent thelower end, a ram projecting from the upper end of each cylinder, apulley on the upper end of each ram, a pair of head pulleys secured tosaid boom, a pair of cables trained over said head pulleys and aroundthe pulleys on said rams with the adjacent ends of said cables fixed tosaid boom, the opposite ends of said cables being fixed at transverselyspaced points on opposite sides of said boom, a reversing control valvefor each cylinder, conduits connecting said cylinders and said valves, afluid pressure supply conduit and a fluid pressure discharge conduitconnected to said valves, an actuating lever on each valve, a platefixed to said king pin for movement therewith, an arcuate slot in saidplate, an opening in said plate through which said actuating leversproject, op osed actuating lever shifting members disposed on oppositesides of said actuating levers, said members being mounted at one endfor free pivotal movement on said king pin and clamp means on eachmember extending through said slot for fixing each member in adjustedangular position whereby said levers and control valves will beperiodically actuated to alternately connect said fluid pressure supplyconduit to said cylinders, to lengthen and shorten said cables therebycontinuously and automatically swinging said boom back and forth throughan are determined by the position of said members on said plate.

References Cited in the file of this patent UNITED STATES PATENTS400,798 Russell Apr. 2, 1889 497,216 Rogers May 9, 1893 665,684Hetlesaeter Jan. 8, 1901 2,021,066 Huxford Nov. 12, 1935

